Hello i noticed that on newest dev-craftbukkit some plugins like: http://dev.bukkit.org/server-mods/survival-games/ and http://dev.bukkit.org/server-mods/paintball_pure_war/ have a BIG bug! for example with Survivalgames, when you are playing and you leave the server you arent able to rejoin the server because of the error " Same nick already playing" the same thing with the paintball plugin (if you join the lobby)...so i think its a bug from craftbukkit and not the plugins itself.+ i hope craftbukkit will bring out a new dev build
for naow make sure they type /sg leave or how ever you leave a lobby, that's you best bet until the updates.
I've been having the same issue. Fills 80 slots fast as When they disconnect while in MobArena, hunger games or paintball it creates a copy of the player at the spawn